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Trigeminal Neuralgia – Complete PLAB 2 Guide


A patient presenting with brief, electric shock–like facial pain triggered by shaving or touch is a classic PLAB 2 station.

This guide gives you a structured, scoring approach.


Definition

Trigeminal neuralgia is a condition affecting theTrigeminal nerve, causing sudden, severe facial pain due to nerve hypersensitivity.


Presenting Symptoms


Pain Characteristics

  • Sudden, electric shock–like pain

  • Unilateral

  • Lasts seconds to minutes

  • Occurs in recurrent episodes


Triggers (Key Diagnostic Feature)

  • Shaving

  • Brushing teeth

  • Washing face

  • Talking / chewing

  • Light touch

  • Cold wind


Typical Pattern

Trigger → sharp pain → stops completely → normal between attacks

Aetiology (Why It Happens)


Most Common Cause

  • Neurovascular compression of the trigeminal nerve


Secondary Causes (Important)

  • Multiple sclerosis

  • Tumors (e.g., cerebellopontine angle)


Examination


Key Principle

Examination is NORMAL in classical cases

What to Examine:

  • Cranial nerves (especially trigeminal nerve)

  • Facial sensation (V1, V2, V3)

  • Corneal reflex

  • Jaw movements


Expected Findings:

  • Normal neurological exam

  • Pain may be triggered on touch


Red Flags (Suggest Secondary Cause)

  • Sensory loss

  • Bilateral symptoms

  • Persistent (non-episodic) pain

  • Other cranial nerve deficits



Investigations


Key Principle

Clinical diagnosis

Blood Tests (Baseline)

  • FBC, U&E, LFT → Normal

  • Blood sugar → rule out neuropathy

  • ESR/CRP → if suspect


    Giant cell arteritis


Imaging

  • ❌ X-ray face → Not required

  • ✅ MRI brain → If:

    • Atypical features

    • Young patient

    • Poor response


Management


First-line Treatment

  • Carbamazepine


How to Explain to Patient

  • Regular painkillers don’t work for nerve pain

  • Start low dose and increase gradually


Side Effects

  • Drowsiness

  • Dizziness

  • Nausea / vomiting

  • Unsteadiness


Who Starts Treatment?

  • GP can start treatment



Referral


Not Required Initially (Typical Case)


Refer to Neurology If:

  • Red flags present

  • Poor response to treatment

  • Suspected secondary cause

  • Considering surgery



Triggers & Risk Factors


Triggers

  • Light touch

  • Shaving

  • Chewing

  • Cold wind


Risk Factors

  • Age > 50

  • Female

  • Neurovascular compression

  • Multiple sclerosis


Lifestyle Factors

  • Not proven causes

  • Alcohol → may trigger in some

  • Smoking → no strong association



Key Differentials


Trigeminal Neuralgia vs Giant Cell Arteritis

Feature

Trigeminal Neuralgia

Giant Cell Arteritis

Pain

Electric shock

Dull headache

Duration

Seconds

Continuous

Trigger

Touch

No trigger

Exam

Normal

Tender artery

Vision risk

❌

🚨 High



PLAB 2 Explanation Line

“This is a nerve-related pain where even light touch like shaving can trigger brief, sharp pain. The good news is it’s a known condition and we can treat it effectively.”

One-Liner for Exams

“Brief, unilateral, electric shock-like facial pain triggered by touch, with a normal neurological examination.”

Final PLAB 2 Tips

  • Always mention triggered pain

  • Emphasise normal exam

  • Say clinical diagnosis

  • Start carbamazepine

  • MRI only if red flags

  • Reassure: not cancer, treatable

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